Adjust Idle

Beginning in 1985, some engines were available with a throttle body fuel injection system. And all engines were fuel injected starting in the 1986 model year. By 1992 a central multi-port fuel injected engine became available as well. All fuel injected engines are controlled by a computer. This computer regulates idle speeds. It also supplies the correct amount of fuel during all engine operating conditions. No periodic adjustments are necessary or possible. Therefore there are no adjustments to be made.

When the idle is high, check for a vacuum leak. If it is low try cleaning the throat of the throttle body and check your air filter. When the idle seems to be stuck, clean or replace the IAC – Idle Air Control valve.

IAC Replacement

1.Disconnect the negative battery cable.
2.Disengage the electrical connector from the idle air control valve.
3.Loosen and remove the threaded IAC control valve and gasket using either a 1 1 ⁄ 4 in. (32mm) wrench, J-33031, or equivalent.To install:

WARNING
Before installing a new idle air control valve, measure the distance that the valve extends (from the motor housing to the end of the cone); the distance should be no greater than 1 1 ⁄ 8 in. (28mm). If it is extended too far, damage may occur to the valve when it is installed.

4.Measure the valve pintle extension. To retract the pintle on a NEW valve, use firm thumb pressure and, if necessary, rock the pintle with a slight side-to-side motion. BUT, if reinstalling a used valve on which the pintle is extended further than specification, an IAC tester MUST be used to electrically retract the pintle.
NOTE: Do not attempt to physically retract a pintle on an IAC valve that has been in service, the force may damage the pintle threads. The force required to retract the pintle is only safe on NEW IAC valves.

5.Install the IAC valve and gasket to the throttle body and tighten to 13 ft. lbs (18 Nm).
6.Engage the valve electrical connector.
7.Connect the negative battery cable.
8.Reset the IAC valve pintle: A.There are 2 possible methods to resetting the IAC valve. First, depress the accelerator pedal slightly, then start and run the engine for 5 seconds. Shut the engine OFF for 10 seconds, then restart it and check for proper idle operation. If this does not work, start and run the engine until it reaches normal operating temperature. Drive the vehicle and the IAC valve will reset once vehicle speed is above 35 mph.